Table 2.

Mammographic density and serum biomarkers at baseline and change at 6, 12, and 24 months compared with baseline

Vitamin DPlacebo
OutcomeTimeframeNMean (SD)NMean (SD)P value
Mammographic density (%)Baseline7638.6 (18.0)6935.0 (19.0)0.24
Change at 12 months73−0.3 (8.0)641.5 (8.8)0.22
Change at 24 months63−1.2 (8.0)571.6 (10.3)0.10
Serum 25(OH)D, ng/mLBaseline9023.9 (7.2)8823.7 (8.4)0.93
Change at 6 months7619.2 (10.6)725.8 (10.9)<0.01
Change at 12 months6418.9 (8.9)622.8 (8.0)<0.01
Serum 1,25(OH)D, pg/mLBaseline9051.4 (23.6)8850.8 (22.5)0.87
Change at 6 months7648.8 (33.6)7213.0 (27.8)<0.01
Change at 12 months6442.7 (26.0)625.2 (16.7)<0.01
Serum PTH, pg/mLBaseline8734.0 (18.7)8834.0 (19.0)0.99
Change at 6 months744.5 (15.7)720.2 (16.6)0.09
Change at 12 months61−7.2 (15.7)610.5 (17.3)0.01
Serum IGF-I, ng/mLBaseline90158.8 (67.0)89140.8 (56.6)0.05
Change at 6 months77−6.2 (42.2)733.9 (30.8)0.10
Change at 12 months64−9.8 (46.6)62−1.8 (34.3)0.28
Serum IGFBP-3, μg/mLBaseline905.1 (1.0)895.0 (1.0)0.53
Change at 6 months770.1 (0.7)730.1 (0.6)0.72
Change at 12 months64−0.2 (0.7)620.04 (0.8)0.07
IGF-I/IGFBP-3 ratio (x 10−3)Baseline9030.9 (11.3)8928.3 (10.5)0.11
Change at 6 months77−1.3 (8.6)730.04 (7.1)0.32
Change at 12 months64−0.2 (9.8)62−0.9 (7.6)0.65
  • Abbreviations: 1,25-dihydroxyvitamin D (1,25(OH)D), 25-hydroxyvitamin D (25(OH)D), insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3, parathyroid hormone (PTH).